Stop joint for fluid filled cables



Mann 29, 1938. E Q EBY' STOP TOINT FOR FLUID' FILLED CABLES vIII-TVeVtG-V: ELQene D. E155, b' fwsw@ gHis Attorney.

Filed Feb. l24, 195e Patented Mar. 29, 1938 UNITED STATES PATENT OFFICEEugene D. Eby, Pittsfield, Mass., assignor to General Electric Company,a corporation of New York Application February 24, 1936, Serial No.65,309

11 Claims.

It is the practice in cable installations utilizing a liquid, such asdegasied oil, for example, to improve the character of the fibrousinsulation which is applied to the conductor, to provide stop joints atspaced intervals 'to limit the hydrostatic head due to liquid pressureas, for example, where the cable or a portion thereof is located on aslope, and also to segregate or divide the length of cable into sectionsso as to prevent draining of the entire cable or a large portion thereofin the event of a leak in any one of the connected reel lengths of whichthe cable reasonably true.

is composed.

As heretofore constructed, these stop joints are relatively large andexpensive and for that reason the number of such joints in a giveninstallation is generally less than is desired from the viewpoint ofsegregation. Another controlling factor in most, if not all, cases isthe size and spacing of the existing manholes in which the joints haveto be located. In some cases, new manholes have to be constructed or oldones enlarged in order to alford the necessary space for the joints andthe trained ends of the cables connected thereto. This is furthercomplicated in an installation of single conductor cables operatingthree phase in that three such joints have to be located in the samemanhole along with a considerable amount of other apparatus includingliquid containing reservoirs for the cables.

Heretofore;L these stop joints have required the use of large'moldedporcelain insulators which are expensive to manufacture, are relativelyeas'- ily broken, and are relatively thick and consequently heavy. Beingmade of molded material which is afterwards fired at a high temperature,there is considerable loss due to warpage and breakage and to failure ofthe nished insulators to conform to the required dimensions. Because ofthe latter fact the insulators have to be made larger than wouldotherwise be necessary. They Cannot be machined and the only permissiblefinishing operation is that of grinding certainsmall surfaces at thevends to render them A typical stop joint wherein molded porcelaininsulators are employed and which has been extensively used isillustrated in my Patent 1,819,882 issued August 18, 1931.

By reason of the improved construction forming the subject matter of thepresent application, I am able to reduce the overall length of a stopjoint for agiven installation approximately 27% over one for the samepurpose using molded porcelain insulators, its diameter by approximately50%, and its volume. meaning thereby the j cubical contents of the jointcasing, by approximately four fths. j

My invention has for its object the provision of an improved stop jointfor fluid filled cables which is substantially smaller, less expensiveand less liable to injury than those which have heretofore been used.

For a consideration of what I believe to be novel and my invention,attention is directed to the accompanying description and the claimsappended thereto.

In the accompanying drawing, which is illustrative of my invention, Fig.l is a view partly in longitudinal section and partly in elevation of astop joint; Fig. 2 is a cross-section on line 2--2 of Fig. l; Fig. 3 isa cross-section on line 3-3 of Fig. 1; Fig. 4 is a detail sectional viewof a part of the construction; Fig. 5 is a perspective View of apreformed conical tube insulator; Fig. 6 is a sectional detail of one ofthe conductor connecting members, Fig. '7 is a detail view illusntrating the electrostatic shield over the clamp that unites theconnector members, and Fig. 8 is a. detail view of `a connector suitablefor solid type cable,

Since both ends of the joint are similarly constructed, a description ofone end will be sufficient. 'l indicates a hollow stranded conductor,

the channel or core 8 of which is filled with liquid insulation under apressure above that of the atmosphere. As an illustration, degasiiledoil may be employed as the liquid. Surrounding the conductor arenumerous layers 9 of fibrous insulation applied in the factory in theform of relatively narrow tapes or ribbons. These layers are impregnatedwith the oil filling the channel. Surrounding the insulation and snuglytting it is an impervious lead or equivalent sheath I0. The factoryapplied insulation is cut away to `form small steps Il, as best shown inFig. 4, to expose the copper or other strands of the conductor near theendthereof. The bared end of the conductor is inserted in a socket l2formed in the connector member i3, best shown in Fig. 6. This member hasa central tube Il, the outside diameter of which corresponds to the boreof the hollow conductor, a head l5, and an annular part I5 which formsthe outer Wall of the socket for the conductor while the tube H formsthe inner wall. The part I6 is provided with a suitable number of smallopenings I1 through which string solder is introduced for the purpose ofilrmly uniting the conductor and connector member. The central part ofthe member is enlarged to form the head which has a peripheral groove I8and one or more radial ports or passages I9 communicating therewith andwith the central bore or passage of the member. The groove I8 is ineffect a small annular chamber which feeds liquid to and receives itfrom the channels in the cone-shaped insulator as will appear later. Theliquid in the channel of the conductor under operating conditions isfree to ow into and through tube I4, radial ports or passages I9 andgroove I8. One side of the member has a tubular extension 20, which isscrew threaded internally. The bore oi the tube I4 and of the extension20 are both screw threaded to receive a small plug 2|, Fig. 1, which actas a valve. 'Ihe right hand end of the extension is also provided withadditional screw threads to receive the larger plug 22, Fig. l, whichalso acts as a seal. The purpose of these valves or plugs will bedescribed later.

As previously indicated, both ends of the joint are alike and for thatreason, two connector members I3 are provided. To unite them, two halfclamps 25 and 26 are employed having internal screw threads to engagethose oi the extensions 20. Care should be exercised in making the jointnot to distort the extensions 2@ in any way, especially during theoperation of uniting the strands of the conductor with the soketed partsof the connector members by soldering or compressing the parts lo. notto injure the threads on the extensions il@ because if injured, theywill not properly nt the internal threads of the clamps. The half clampsare united by a suitable number of screws 2l, Fig. 3, having sockets intheir heads to receive suitably formed wrenches. Only two screws areshown because their positions coincide with the the section butordinarily four or sin screws will be employed. The main thing is to beable to y exert suicient pressure on the respective threaded surfaces ofthe parts to insure good. electrical conductivity from cable to cable.The provision oi the extensions ill and the divided clamps arranged asshown also maire a strong mechanical construction of reasonable axiallength. The clamp lls the entire space between the ends ot the coneinsulators to be referred to later, except for two thin clmping nuts,and has approximately the same diameter. as the small ends of the cones.Because of the necessary openings for the screws 2l which may presentsharp irregular surfaces, a covering of thin metal 55 is applied overthe clamp to act as an electrostatic shield. 'The advantage of a smoothclamp either alone or in combination with a metal shield or coveringresides in the fact that a smooth practically unbroken surface isprovided over which a reinforcing tape insulation may be easily andsmoothly wound in continuous layers. Where irregular surfaces exist inthe region of the connector members, it is impractical to use such tapewindingsand other and more expensive means have to be employed and whichsubstantially enlarge the overall diameter of the joint and alsoincreases the cost. Moreover, the use of relatively large smooth metalsurfaces reduces the tendency for the concentration of high electricalstresses at any point. The reinforcing insulation 4I is deslrablycovered inside and out by layers or varnished sills tape 29 in themanner illustrated in Fig. 4.. As previously stated, the factory appliedinsulation is removed in a manner to form steps and to thereby expose.the conductor. After each conductor is united with its connector member'conditions are generally unfavorable.

lt is also important I3, as by soldering or compressing, it is necessaryto reinsulate it, which means that the work must be done in a. manholeunderground where For this purpose, fibrous insulation 2l such asvarnished cloth tape for example is employed and wrapped on layer bylayer with overlapping turns. This eld applied insulation covers a partof the factory applied insulation as indicated at the left hand end ofFig. 1, and also covers the part I Q of the socket of the connectormember. Some kinds of insulation in common use for such purposesadversely affect the degasied oil used in the cable by contaminating itto a limited extent. Where it is necessary or desired for any reason touse such insulation, it becomes important tov prevent the oil fromhaving direct access thereto and thereby being subject to contamination.This is done by providing internal and external coverings :forprotecting the reinforcing wrapped on insulation 28. For this purpose,any suitable insulating material may be employed which is impervious tooil and which has no objectionable effect thereon nor the oil upon theinsulation. In other words, material whose eiiect on the oil or otherinsulating liquid is neutral. For example, varnished silk tapes 2Q maybe applied with well overlapped turns. The inner layer is applied tothe4 stepped portion of factory applied insulation and the outer layerto the peripheral surface of the reinforcing insulation. One or morelayers of these tapes may be used ln each case. lin this manner, thewrapped on insulation' 2li is fully prevented, both on the inside andoutside, from adversely aectlng the oil. Where insulation is availablewhich does not adversely affect the degaslded oil in the cable, thecoverings alcove mentioned may be omitted.

`By carefully. applying the insulation to and using a suitable gauge,:lt can be made to coniorm with a reasonable degree ci 'accuracy to thedesired radial dimensione along its axial length, but much depends uponthe skill care exercised by the workman, especially since the outersurface is of the iorm oi a slightly tapered cone.

Instead' of using molded porcelain insulators which, as previouslystated, are open to numerous objections, l use for the purpose preformedinsulators made of fibrous material such as paper arranged in layers orlamlnations and a heat hardened binder such as a phenolic condensationproduct. Because the insulator is in the form oi a cone and has anintnrned end 3l and a collar 32, certain special steps are required inits manufacture. One suitable method of procedure is as follows. Asuitable form or dummy is rst provided that substantially conforms tothe shape and size of the finished lnsulator. Over the form are appliedcurved segmental strips of paper which have been previously coated ortreated with a binder, such as a phenolic condensation product. Eachstrip makes one or approximately one turn about the form with its edgesparallel to the ends of the iorm. The part oi the paper iorming thepor-v tion of the cone of smaller diameter is slotted and the spaces soformed are closed up when external pressure is applied. This arrangementprevents wrinlcling. The inturncd end is formed by bending inwardly theends of the narrow pieces between the slots. The paper is applied to theform piece by piece so as to form layers or laminations with the jointin each layer overlapped by the next outer layer. To iorm the Lil collar32, a band of paper of the desired thickness isvapplied. If additionalthickness is desired for the inturned end, a limited amount ofadditional treated paper may be applied at this point. The paper thusapplied to the dummy may be temporarily held in place either bysoftening the binder by heat to render it sticky or by other bindingmeans. As thus formed, the insulator conforms approximately to its finalshape and size. 'Ihe next step is to insert the assembly into a moldwhich has been carefully finished to the desired shape and dimensions.While in the mold, the assembly is subjected to heat and to heavypressure internally and externally which has the effect of causing theassembly to conform to the proper shape for the insulator and the binderto harden and unite all of the papers into a dense, integral mass. Aninsulator so formed has much better dielectric strength than porcelainand for that reason the section may be made much thinner with theultimate result of decreasing the diameter of the joint as a whole. Itis tough and well adapted to withstand stresses and rough handling. Inaddition to the foregoing, it can be machined without difficulty,thereby permitting any or al1 parts thereof to be made to definitedimensions. It also avoids the use of thick heavy end flanges of largediameter which are so necessary with porcelain parts that are subjectedto stresses and have to have fluid tight joints thereby decreasing thelength of the joint. In general, such an insulator can and does make areasonably close fit over the reinforcing insulation 28 and because ofits strength and freedom from fracture, it can if necessary be forcedlongitudinally into place in the event that the insulation 28 is a trieirregular and large in one or more spots. Since in the joint, it isnecessary to ensure a free but nevertheless small passage for the oil orother fluid from the channel 8 of the conductor to the end chamber 33 ofthe joint casing, a number of longitudinal grooves 35 are molded ormachined inside the conical insulation extending from the cuter endthereof to approximately the inturned end 3|. In any event, 'they shouldbe in free communication with the annular groove i8 and the radial portsor passages I8 in the head portion of the connector member. The grooves35 ensure a free passage for oil even though the cone is forced over theinsulation 28 to an extent that would otherwise cause an obstruction ordam to be formed which would prevent or unduly limit the movement of oilbetween the chamber 33 and the channel 8 of the conductor. In the eventthat a reduced diameter of the cone insulator is not vof paramountimportance, it may be made of larger internal diameter in which case thegrooves 35 may be omitted, but since any increase of diameter of thecone results in a correspondingflncrease of diameter of the surroundingparts and increased cost, such procedure is not generally recommended.'I'he oil in the space or passage between the cone insulator and thereinforcing insulation is under considerable electrical stress, being incontact with the connector member. For that reason, the thickness of theoil body in the passage should be as small as possible consistent withmaintaining a free passage, and because of the stresses the passageshould be as long as possible without unduly increasing the length ofthe cone insulator to prevent leakage of the current. The joint hereinillustrated is designed for a cable operating at 69,000 volts but is notnecessarily limited to this or any other voltage. Changes in voltagesmay necessitate minor changes in construction but the Although varrangement will remain the same. the groove |8 is shown as being in thehead of the connector member, it may be in the insulator and should, ofcourse, open into the grooves 35.

The inturned end 3| of the insulator which is made of thinner sectionthan is possible with porcelain for the same purpose is clamped betweenthe head |5 of the connector member and a nut 36 which is screwed on thepart 20 of said member, suitable packings being provided on both sidesof said end to form a fluid tight seal. The nut is of substantially thesame diameter as the clamp to facilitate the operation of insulating byavoiding depressions, etc.

The large or outer end of the cone insulator is secured by means of thecollar 32 thereof as follows: Inside of the joint enclosing casing andforming an integral part thereof, as by soldering or brazing, is a ring31 having an internal shoulder to receive the collar 32 of the insulatorand a packing ring and also an internally threaded portion to receivethe annular nut 38. In -elect the ring and internally threaded portionthereof form a part of the joint casing and also form a suitably rigidstructure which will not be distorted when the nut is turned to clampthe insulator. The diameter of that portion of the ring which receivesthe collar 32 of the insulator is slightly larger than the collar tofacilitate free seating of the parts. In addition to serving as aclamping nut, it is extended in the form of a cone 39 to form a groundshield, thereby simplifying the construction by decreasing the number ofparts and making it easier to assemble.

Referring now to the small valve or plug 2| and the larger valve or plug22 both in theconnector member, when the cable reaches the point ofinstallation, it is lled with oil or other insulating liquid and thefirst step is to upturn the end of the cable to form a trap to prevententrance of air, after which the cable end cap is removed and theconnector member assembled in place and soldered or otherwise secured inplace. A limited amount of oil is then permitted to escape through thechannel 8 and radial passages i9 to flush and carry out air as byapplying pressure to the oil at the far end of the cable. Before bendingthe cable to a horizontal position, the small plug 2| is screwedinwardly until it closes all of the radial passages I9 when all furtheroutward flow of oil from the channel 8 is stopped. The pressure appliedto the oil is then increased and maintained during the remainingoperations. The cable may then be bent to a horizontal position, thefactory insulation removed by steps, and the stepped part reinforced andthe cone insulator 30 slipped end- Wise to place and clamped inposition. After both cable ends have been prepared, evacuated and lledwith oil through conduit 50, and just prior to uniting the extensions 20by the clamping means, the small plug 2| is backed out by a suitabletool to uncover the radial passages i9. 'Io prevent it from beingentirely removed from the connector member, a stop means such as a ringor shoulder 40 is provided. The larger plug 22 is then tightly screwedinto place as a further means of preventing any leakage of oil from onecable to the other. Having definitely closed the parts of the connectormembers, one with respect y forcing insulation 4| is wrapped around theclampjthe electrostatic shield, provided such a shield is required bythe construction of the clamp, and over a substantial portion of thecone insulators of both parts or halves of the joint.

The casing is made in several parts to facilitate the assembly. The endparts or sections 42 are wipe soldered to the cable sheaths. Theintermediate sections 43 are in turn wipe soldered at 44 to the endsections, andthe intermediate sections are united by the Wipe solderedjoint 45. 'Ihe adjacent ends ofv the sections are telescoped for a shordistance so as to afford a. suitable support for t various sections. Asadditional supports for the outer ends of the intermediate sections, theconed ends of the ground shields 39 are shouldered or enlarged asindicated at 46. As a further means of insuring the centralizing of thecasing with respect to the axis of the joint, insulating blocks 41 areprovided and angularly spaced. These may be held in place by groovingthe peripheral portion of each block and applying a binding band 48thereto.

In some cases, it is important to insulate the sheath of one cable fromits connected cable in order to prevent the circulation of sheathcurrents 'This may effectively be done by the use of an insulator 49which is secured to the adjacent separated ends of the metal parts ofone of the intermediate casing sections 43. The adjacent ends of thesection have numerous parallel grooves and the insulator, which is madeof a compound, is molded under heat and pressure around the ends, thecompound filling the grooves and being firmly anchored therein.

To admit insulating liquid to the cable and receve it therefrom, aconduit 50 is provided at each end of the casing and opening into theend chambers 33. The conduits 50 are connected to suitable reservoirs(not shown) containing the same kind of liquid as that in the channel ofthe cable, said reservoirs being arranged to maintain superatmosphericpressure within the cable, In order to form a rm support for eachconduit 50,

the ring 31 is extended beyond that required as a support for the coneinsulator 30, and the conduit is screw threaded into the extension. Tomaintain the insulation 4| which overlies the cones 30 and the clampsfully impregnated at all times, ak conduit 5| is provided which opensinto the chamber 52 surrounding the parts of the joint. This conduitwill usually be connected to a supply reservolr. As a general thing, itis desirable to use the same kind of liquid insulation in the casingchamber 52 that is used in the cable. In the bottom of the central partof the casing is located a vdrainage opening which is normally closed bya plug 53. Conduits 50 and 5I at the right hand end joint may beconnectedtogether and both supplied from the same reservoir. 'I'heconduits 50 may be connected with a conduit containing an insulatingjoint. f

My invention'has been described in connection with what are termediluid'lledcables, the conductors of .which have a central channelcontaining a body of thin insulation which is in liquid t form at alltimes, but it is also applicable to cables of the sol-called solid typewhere the impregnating material such as heavy oil has a tendencyespecially when heated by the current flowing in the conductor to moveor migrate from a portion of the cable of higher elevation to a portionof lower elevation, as for example where the cable is laid on the sideof a hill or slope. Under these conditions, the migration of the heavyoil has a tendency to cause dry spots in the portion of the cable at thehigher elevation and abnormally increase the'pressure at the lower endor portion. When used in connection with so-called solid cable, the samegeneral construction is followed, as shown in Fig. 8 with the exceptionthat the connector members are made solid or plugged to produce the sameeifect and the tube I4, radial port I9 and valves 2l and 22 may beomitted or plugged because unnecessary. To simplify manufacture it isdesirable to make the connector members initially alike and subsequentlyto make changes where necessary. n

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a stop joint for cables, the combination of a pair of connectormembers, each having a socket, an extension and a head located betweenthe socket and extension, cables having factory applied brous insulationthereon which is impregnated with an insulating material that tends toiiow from a high to a lower point of each cable, said factory appliedinsulation being reduced in thickness toward the sockets tov formtapered surfaces, reinforcing insulation wrapped around the ends' of thecables including a portion of the factory applied insulation whichremains undisturbed to form cone shaped bodies, a preformed cone shapedinsulator for each cable end which encloses the head of one connectormember and surrounds the reinforcing insulation, said insulator beingcomposed of fibrous material and a hardened binder arranged to form alaminated body closely surrounding the reinforcing insulation and havingan inturned end, a means for clamping the inturned end of each insulatorin contact with the head of a connector member to make a fluid tightjoint, a clamp uniting the extensions on the connector members whichpresents a smooth peripheral surface of relatively large diameter, awrapping of tape insulation applied in contacting layers directly overthe clamp and the adjacent ends of the cone shaped preformed insulators,an enclosing casing for the ljoint, and means located at each end of thecasing forming a support for the large end of the cone insulator, saidmeans and insulator deilning with the casing independentnon-communicating end chambers.

2. In a stop joint for fluid filled cables, the combination of a pair ofhollow connector members, each having a socket, an extension, a headlocatedv between the socket and extension, and an open port, insulatedconductors having hollow channels filled with fluid insulation, the endsof the conductors being secured in the sockets with the channels incommunication with the ports, the insulation on each of the cables beingreduced in thickness toward the socket to form a taper, a clamp whichunites the extensions, reinforcing insulation wrapped around the ends ofthe cables, a cone shaped insulator'for each cable end which enclosesthe head on one connector member and'surrounds the reinforcinginsulation on the cable end, said insulator being composed of iibrousmaterial and a binder arranged to form a laminated body having aninturned end, a means for holding the inturned end of each insulator incontact with the head on .a connector member to make a fluid tightjoint, a wrapping of insulation directly over the clamp and portions ofthe adjacent ends of the cone-shaped insulator applied in contactinglayers, an enclosing casing foi* the joint, a means located at each endof the casing forming a support for the large end oi a cone insulator,the said means and insulator defining with the casing wall an endchamber which is in free communication with the channel of the conductorand the port in the connector, and conduit means through which fluidinsulation may ilow from and enter one of the end chambers.

3. In a stop joint for cables, the combination of a pair of hollowconnector members, each having a socket, an extension, a head locatedbetween the socket and extension, andan open port in the headcommunicating with the interior of the member, onductors havinginsulation thereon impregna d with fluid insulation, the ends of thecondu rs being secured in the sockets, the insulation on'the cablesbeing reduced in thickness toward the sockets to form a taper, a clampwhich unites the extensions and presents a smooth peripheral surface,reinforcing insulation wrapped around the ends of the cables and aportion of each of the sockets,v a cone shaped insulator for each cableend which encloses the head on one connector member and covers thereinforcing insulation on the cable end, said insulator being composedof highly compressed fibrous material and a binder arranged to form alaminated body having an inturned end, a means for holding the inturnedend of each insulator in contact with the head on a connector member tomake a fluid tight joint, an enclosing casing for the joint, ashouldered and internally threaded ring located inside of thecasing ateach end thereof and sealed thereto, each of said shoulders forming asupport for the large end of a cone insulator, and nuts inside of thecasing each holding the end f an insulator against a shoulder, said ringand insulator defining with the casing wall a chamber which is in freecommunication with the channel g of the conductor and the port in theconnector member, and insulation surrounding the clamp.

4. In a stop joint for fluid filled cables, the combination of a pair ofhollow connector meinbers, each having a socket, an extension, a headlocated between the socket and the extension, and an open port incommunication with the interior of the member, insulated conductorshaving hollow channels filled with iluid insulation, the ends of theconductors being secured in the sockets with the channels incommunication with the port, the factory applied insulation on thecables being reduced in thickness toward the sockets to form a taper, aclamp which unites the extensions, reinforcing insulation wrapped overthe ends of the cables and a portion of each of the sockets, a coneshaped insulator for each cable end which encloses the head on oneconnector member andk covers the reinforcing insuu lation on theadjacent cable end, said insulator being composed of fibrous materialand a binder arranged to form a laminated body having an inturned end,longitudinal grooves located in the inner wall of the insulator forestablishing a passage ior fiuld between the port in the connectormember and the chamber beyond the end of the insulator, a means forsupporting the large end Yof the insulator, a chambered casing withwhich the grooves communicate, and a conduit for admitting fluid to andreceiving it from the chamber of the casing and the grooves.

5. In a stop joint for fluid filled cables, the combination of a pair ofconnector members each having a socket, an extension, a head locatedbetween the socket and the extension, an open port, a longitudinalcentral passage communicating with the port, a portion of which is screwthreaded, a screw threaded valve mounted in the pasthe socket, awrapping of tape insulation over the factory appli ,-d insulationforming a cone, a conical insulator surrounding the wrapped oninsulation which is composed of compressed fibrous material and abinder, there being a pas- Sage for fluid between the two insulationswhich is in communication with the port in the connector member, aeasing for the joint having a chamber which is in communication with thepassage, means for securing the small end of the conical insulator tothe head of a connector member, and means for securing the large end ofthe insulator to the casing.

6. In a stop joint for fluid filled cables, the combination of aconnector member having a socket, a head, a central passage andoutwardly opening ports which are in iree communication with thepassage, an insulated cable secured in the socket which has a centralfluid containing channel communicating with the passage, a preformedinsulator closely surrounding the insular tion on the cable which iscomposed of compressed fibrous material and a binder, means for securingthe insulator to said head, grooves in the inner wall of `the preformedinsulator for conveying fluid to and from the ports, an annular chamberwith which the ports and the grooves are in free communication, and acasing for the joint having an end chamber with which the grooves are incommunication.

7. A'eable joint comprising a pair of aligned connector members eachhaving an enlarged head midway of its length with an externally threadedextension of lesser diameter on one side of the head, a socket in theother side of the head to receive and hold the conductor of a hollowcore cable, a longitudinal conduit within the member for iiuidinsulation, an outwardly opening port in the head communicating with theconduit, a divided internally threaded current carrying clamp, thethreads oi which engage those on the extensions, 'means for uniting theparts of the clamp about the threaded extensions, and a controllablevalve means within each of the exten-1 sions and enclosed by the clampfor closing the port while the members are exposed preparatory touniting them and also for shutting oi the passage oi fluid from theconduit of one member into that of another,

8. A cable joint comprising a pair ci aligned connector members eachhaving an enlarged head midway of its length with an externally threadedextension of lesser diameter on one side of the head, a socket on theother side of the head to receive and hold the conductor of a hollowcore cable, a longitudinal conduit within the member containing duidinsulation and through which it is free to escape'during an assemblyoperation of the parts of the joint, said conduit having screw threadsat its end remote from the head, a screw threaded plug accessible fromthe outer end'of each of the extensions for definitely stopping theoutward passage of fluid through the extension form the hollow core oione cable lil() conductor intothat of the other, a divided internallythreaded current carrying clamp, the threads of which engage theexternal threads on the extensions, said clamp enclosing both of thethreaded plugs, and means for rmly uniting the parts of the clamp aboutthe threaded extensions.

9. A cable joint comprising a pair of aligned connector members eachhaving a head midway of its length with an externally threaded extensionon one side of the head, a socket on the other side to receive and holdthe conductor of a hollow core cable, a longitudinal conduit within themember containing fluid insulation, a port in the head extending fromthe conduit to the periphery thereof, and a screw threaded plug withineach extension whereby the port may be opened or closed to control theoutward passage of uid therefrom, a divided internally threaded currentcarrying clamp, the threads of which engage the external threads on theextensions, said` clamp surrounding lthe plugs, means for uniting theparts of the clamp about the threaded extensions, and a thin metalcovering for the surfaces of the clamp acting as an electrostatic shieldtherefor and presenting a smooth exterior surface to receivesubsequently applied insulation.

10. A stop joint `yfor cables comprising a pair of connector members,each having a socket and an extension, one of said members having a head30 located between its socket and its extension, cables 40- brousmaterial and a hardened binder arranged to form a laminated body, saidbody having an inturned inner end, means for clamping the inturned endto the head of said member to make a iluid tight joint, an enclosingcasing, a ring having a shoulder which is arranged to receive the outerend of the laminated insulator and is also internally threaded, and anannular nut through which the insulator extends, said shoulder and nutco-operating to center the insulator with respect to -the cable axis andalso form a uid tight seal between the interior of the insulator and thepart of the casing surrounding the nut.

11. In a cable joint, the combination of a first connector member havinga socket, a passage for liquid communicating with the socket, a head. aport in the head communicating with the passage, and an extension, ahollow core insulated conductor having a bare end located in the socket,a body of uid insulation within the passage and core, a secondconductor, a second connector member secured to the extension and alsoto the second conductor for uniting the conductors electrically andmechanically, eld applied insulation surroundingthe first connector, anenclosing casing for the joint having an internal shoulder, a preformedinsulator closely surrounding the rst connector member and theinsulation thereon comprising compressed laminated fibrous material anda hardened binder, the insulator having a longitudinally extendinginternal groove communicating with the port in the head for conveyinguid to and from the hollow core conductor and passage, means securingone end of the insulator uid tight to the head of the first connectormember, the opposite end of the insulator opening into the casing andengaging the shoulder thereof, the insulator and casing dening a iuidcontaining chamber communicating with the groove, and a clamping nutholding an end of the insulator in engagement with the internal shoulderof the casing.

EUGENE D. lErni.

